STUDIES OF ADULT BRAIN NEUROPOIESIS

描述(由申请人提供)：干细胞在中枢神经系统中的归巢、维持和整合是神经再生和再生神经生物学新兴领域的新课题。所谓的组织特异性干细胞被诱骗成其他组织表型的不同例子，推动了干细胞可塑性的概念。这种改变组织特异性干细胞的命运，诱导转分化，已经在许多不同的生物测试中被报道，使用各种细胞培养和体内条件和操作。这项研究将比较成年啮齿动物大脑中一个持续的神经源性(或称神经生成)区域-室管膜下区(SEZ)及其头端迁移流(RMS)在神经化条件下的归巢、干细胞更新、命运控制和分化，该区域参与包括嗅球在内的前脑结构的持续再生。提出了三个具体的目标，将使用体内和体外桥接生物测定来评估来自脑(多能星形细胞干细胞，或神经干细胞的“NSC”)和血液(“HSC”，造血干细胞)的两个候选干细胞群体。具体目的1将验证一种假设，即特定的细胞外基质分子(Tenascin-C和软骨素硫酸盐蛋白多糖)、细胞表面分子(CD15和CD9)、趋化因子及其受体(SDF-1/CXCR4)由这些细胞和SEZ/RMS表达，以促进干细胞的归巢、维持和整合。AIM 2将通过研究这些分子在移植NSC和HSC后在体内的可能作用，使用敲除动物和针对这些候选归巢/整合因子的功能阻断抗体来进一步测试这一点。最后，目标3将使用组织外植体-干细胞共植的灵敏的形态和电生理学分析来验证NSC和HSC可以在功能上整合在前脑神经起源结构中的假设。在我们了解血细胞转化为脑细胞的潜力之前，我们有必要了解起始细胞群体的干性程度，并阐明干细胞归巢、维持以及整合到受损的中枢神经系统回路中的因素。这里提出的研究还为神经造血细胞和造血细胞的长期培养和整合提供了见解，并着眼于各种脑和血液疾病的治疗方法的发展。

DESCRIPTION (provided by applicant): Homing, maintenance, and integration of stem cells in the central nervous system are rather new topics in emerging fields of neuropoiesis and regeneration neurobiology. The notion of stem cell plasticity has been advanced by different examples of so-called tissue specific stem cells being coaxed into other tissue phenotypes. This altering fate of tissue-specific stem cells, inducing transdifferentiation, has been reported in many different bioassays, using a variety of cell culture and in vivo conditions and manipulations. This proposal will compare homing, stem cell renewal, fate control and differentiation under neuralizing conditions in a persistently neurogenic (or "neuropoietic") region of the adult rodent brain - the subependymal zone (SEZ) and its rostral migratory stream (RMS) that is involved in continual repopulation of forebrain structures including the olfactory bulb. Three specific aims are proposed that will evaluate two candidate stem cell populations from brain (multipotent astrocytic stem cells, or "NSC" for neural stem cells) and blood ("HSC", hematopoietic stem cells) using in vivo and in vitro bridging bioassays. Specific Aim 1 will test the hypothesis that particular extracellular matrix molecules (tenascin-C and chondroitin sulfate proteoglycan), a candidate integrin receptor, cell surface molecules (CD 15 and CD9), and a chemokine and its receptor (SDF-1/CXCR4) are expressed by these cells and the SEZ/RMS to facilitate stem cell homing, maintenance and integration. Aim 2 will further test this, via studying the possible actions of these molecules in vivo following transplantation of NSC and HSC, using knockout animals and function blocking antibodies to these candidate homing/integration factors. Finally, Aim 3 will test the hypothesis that NSC and HSC can functionally integrate within forebrain neurogenic structures, using sensitive morphological and electrophysiological analyses of tissue explants - stem cell coplants. Before we can understand the potential of blood cells to become brain cells, a profound example of transdifferentiation that offers numerous alternative approaches to current cell replacement therapies, it is necessary to understand degrees of stemness of starting cell populations, and also elucidate factors involved in stem cell homing, maintenance, and integration to and within damaged CNS circuits. The studies proposed here also provide insights into long term culturing and integration of neuropoietic and hematopoietic cells, with an eye toward the development of therapeutics for a variety of brain and blood diseases.